WO2018100923A1 - Lc resonator and lc filter - Google Patents

Abstract

The present invention suppresses deviation of the characteristics of an LC filter from the desired characteristics. An LC resonator (10) according to one embodiment of the present invention is a laminate in which a plurality of dielectric layers are laminated in the lamination direction. The LC resonator (10) is provided with a first capacitor (C1), a second capacitor (C2) and an inductor (L1). The inductor (L1) is connected between the first capacitor (C1) and the second capacitor (C2). One end of the inductor (L1) is galvanically isolated from a ground node (GN) by means of the first capacitor (C1). The other end of the inductor (L1) is galvanically isolated from the ground node (GN) by means of the second capacitor (C2).

Description

LC resonator and LC filter

The present invention relates to an LC resonator and an LC filter including the LC resonator.

Conventionally, LC filters including LC resonators are known. For example, International Publication No. 2007/119356 (Patent Document 1) discloses a multilayer bandpass filter in which a plurality of LC parallel resonators are juxtaposed inside a multilayer body in which a plurality of dielectric layers are laminated. Yes.

International Publication No. 2007/119356 Pamphlet

An LC parallel resonator disclosed in Patent Document 1 includes a line conductor pattern formed on a dielectric layer and a via conductor pattern extending from the capacitor conductor pattern formed on another dielectric layer to the line conductor pattern. And another via conductor pattern extending from the line conductor pattern to the ground electrode. The inductor is connected to the ground electrode via a via conductor pattern.

When current flows from the inductor to the ground electrode and other conductors connected to the ground electrode, the ground electrode and other conductors connected to the ground electrode function as inductors not assumed in the design of the LC filter. Sometimes. In an LC filter that requires a high-accuracy filtering function for high-frequency signals, when the ground electrode and other conductors connected to the ground electrode function as inductors, these are characteristics of the LC filter (for example, insertion loss, Alternatively, reflection loss) can be ignored. However, it is often difficult to assume at what stage the LC filter is designed in what manner the ground electrode is connected to what kind of conductor in the mounted state of the LC filter. Therefore, the characteristics (for example, insertion loss or reflection loss) of the LC filter can deviate from the desired characteristics.

The present invention has been made to solve the above-described problems, and an object thereof is to suppress the characteristics of the LC filter from deviating from desired characteristics.

The LC resonator according to an embodiment of the present invention is a stacked body in which a plurality of dielectric layers are stacked in the stacking direction. The LC resonator includes first and second capacitors and an inductor. The inductor is connected between the first capacitor and the second capacitor. One end of the inductor is galvanically isolated from the ground node by the first capacitor. The other end of the inductor is galvanically isolated from the ground node by the second capacitor.

In the LC resonator according to the present invention, one end of the inductor is galvanically isolated from the ground node by the first capacitor, and the other end of the inductor is galvanically isolated from the ground node by the second capacitor. . Since the inductor is galvanically isolated from the ground electrode connected to the ground node, the ground electrode and other conductors connected to the ground electrode are suppressed from functioning as an inductor. As a result, it is possible to suppress the characteristics of the LC filter including the LC resonator from deviating from desired characteristics.

3 is an equivalent circuit diagram of a bandpass filter that is an example of an LC filter according to Embodiment 1. FIG. It is an external appearance perspective view of the band pass filter of FIG. It is a figure which shows the two grounding conductor patterns arrange | positioned inside the band pass filter shown by FIG. It is a disassembled perspective view which shows an example of the laminated structure of the band pass filter of FIG. It is the figure which planarly viewed the band pass filter shown by FIG. 4 from the Y-axis direction. It is a figure which shows collectively each insertion loss at the time of changing the length (inductance of an inductor) of an inductor via conductor pattern in three steps. It is a figure which shows each insertion loss at the time of changing the area (capacitance of the capacitor contained in a LC series resonator) of a capacitor conductor pattern in three steps. It is a figure which shows collectively each insertion loss at the time of changing the distance (capacitance of the capacitor contained in a LC parallel resonator) of a capacitor conductor pattern and a grounding conductor pattern in two steps. It is a figure which shows collectively each insertion loss at the time of changing the area (capacitance of the capacitor contained in LC parallel resonator) of a capacitor conductor pattern in two steps. 6 is an exploded perspective view showing an example of a laminated structure of a bandpass filter according to Embodiment 2. FIG. It is the figure which planarly viewed the band pass filter shown by FIG. 10 from the lamination direction. It is a figure which shows collectively the insertion loss and reflection loss of the band pass filter shown by FIG.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and the description thereof will not be repeated in principle.

[Embodiment 1]
FIG. 1 is an equivalent circuit diagram of a bandpass filter 1 which is an example of an LC filter according to the first embodiment. As shown in FIG. 1, the bandpass filter 1 includes an LC resonator LC10, input / output terminals P1 and P2, and capacitors C3 and C4.

The LC resonator LC10 includes an inductor L1 and capacitors C1 and C2. One end of the inductor L1 is connected to the ground node GN via the capacitor C1. The other end of the inductor L1 is connected to the ground node GN via the capacitor C2.

The LC resonator LC10 can be considered as an LC parallel resonator in which an inductor L1 and a capacitor in which capacitors C1 and C2 are combined are connected in parallel. Further, the inductor L1 and the capacitor C2 form an LC series resonator SLC.

One end of the inductor L1 is connected to the input / output terminal P1 through the capacitor C3. One end of the inductor L1 is connected to the input / output terminal P2 via the capacitor C4.

When current flows from the inductor to the ground electrode connected to the ground node GN and other conductors connected to the ground electrode, the ground electrode and other conductors connected to the ground electrode are designed for the bandpass filter 1. It may function as an inductor that is not assumed above. In the band-pass filter 1 that requires a high-precision filtering function for high-frequency signals, when the ground electrode and other conductors connected to the ground electrode function as inductors, these are the characteristics of the band-pass filter 1 ( For example, it may have a non-negligible effect on insertion loss or reflection loss. However, it is often difficult to assume at the design stage of the bandpass filter 1 what kind of conductor the ground electrode is connected to in what manner in the mounted state of the bandpass filter 1. Therefore, the characteristics (for example, insertion loss or reflection loss) of the bandpass filter 1 can deviate from desired characteristics.

Therefore, in the first embodiment, one end of inductor L1 is galvanically insulated from ground node GN by capacitor C1, and the other end of inductor L1 is galvanically insulated from ground node GN by capacitor C2. Since inductor L1 is galvanically isolated from the ground electrode connected to ground node GN, the ground electrode and other conductors connected to the ground electrode are suppressed from functioning as an inductor. As a result, it is possible to suppress the characteristics of the bandpass filter 1 from deviating from the desired characteristics.

Further, in the first embodiment, one end of the inductor L1 is galvanically insulated from the input / output terminal P1 by the capacitor C3, and one end of the inductor L1 is galvanically insulated from the input / output terminal P2 by the capacitor C4. Since the inductor L1 is also galvanically isolated from the input / output terminals P1, P2, the input / output terminals P1, P2 and other conductors connected to the input / output terminals P1, P2 are suppressed from functioning as inductors. . As a result, it is possible to further suppress the characteristics of the bandpass filter 1 from deviating from the desired characteristics.

Hereinafter, a case where the bandpass filter 1 is configured as a laminated body of a plurality of dielectric materials will be described. FIG. 2 is an external perspective view of the bandpass filter 1 of FIG. As shown in FIG. 2, the stacking direction (the height direction of the bandpass filter 1) is the Z-axis direction. The long side (width) direction of the bandpass filter 1 is defined as the X-axis direction. The short side (depth) direction of the bandpass filter 1 is defined as the Y-axis direction. The X axis, the Y axis, and the Z axis are orthogonal to each other.

The bandpass filter 1 has, for example, a rectangular parallelepiped shape. The surfaces of the bandpass filter 1 along the direction perpendicular to the stacking direction are defined as a bottom surface BF and a top surface UF. Of the surfaces along the direction parallel to the stacking direction, the surfaces along the ZX plane are side surfaces SF1 and SF3. Of the surfaces along the stacking direction, the surfaces along the YZ plane are referred to as side surfaces SF2 and SF4.

On the bottom surface BF, input / output terminals P1, P2 and a ground electrode GND are formed. The input / output terminals P1 and P2 and the ground electrode GND are, for example, LGA (Land Grid Array) terminals in which planar electrodes are regularly arranged on the bottom surface BF.

A direction identification mark DM is formed on the upper surface UF. The direction identification mark DM is used to identify the direction when the bandpass filter 1 is mounted.

FIG. 3 is a diagram showing two ground conductor patterns 11 and 71 arranged inside the bandpass filter 1 shown in FIG. Although the LC resonator LC10 is disposed between the ground conductor patterns 11 and 71 inside the band pass filter 1, the LC resonator LC10 is not shown in FIG. 3 for ease of illustration. . The structure of the LC resonator LC10 will be described later with reference to FIG.

As shown in FIG. 3, the ground conductor pattern 71 is connected to the ground conductor pattern 11 by each of a plurality of via conductor patterns. The ground conductor pattern 11 is connected to the ground electrode GND by each of a plurality of via conductor patterns. Thus, the ground electrode GND and the ground conductor pattern 11 are connected by each of the plurality of via conductor patterns, and the ground conductor patterns 11 and 71 are connected by each of the plurality of via conductor patterns. The potentials of 11 and 71 can be maintained at substantially the same potential as that of the ground electrode GND.

FIG. 4 is an exploded perspective view showing an example of a laminated structure of the bandpass filter 1 of FIG. As shown in FIG. 4, the bandpass filter 1 is a laminated body in which a plurality of dielectric layers Lyr1 to Lyr8 are laminated in the Z-axis direction. The dielectric layers Lyr1 to Lyr8 are stacked in this order in the Z-axis direction with the dielectric layer Lyr1 on the bottom surface BF side and the dielectric layer Lyr8 on the top surface UF side. In FIG. 4, in order to make the structure of the LC resonator LC10 easier to see, a plurality of via conductor patterns connecting the ground electrode GND and the ground conductor pattern 11 and a plurality of via conductors connecting the ground conductor patterns 11 and 71 are shown. The pattern is not shown.

As described above, the input / output terminals P1 and P2 and the ground electrode GND are formed on the bottom surface BF of the dielectric layer Lyr1. A ground conductor pattern 11 is further formed on the dielectric layer Lyr1. As already described, the ground conductor pattern 11 is connected to the ground electrode GND by each of a plurality of via conductor patterns (not shown).

A capacitor conductor pattern 20 is formed on the dielectric layer Lyr2. The capacitor conductor pattern 20 and the ground conductor pattern 11 form a capacitor C2.

Capacitor conductor patterns 51 and 52 are formed on the dielectric layer Lyr5. Capacitor conductor patterns 51 and 52 are connected to input / output terminals P1 and P2 by via conductor patterns V51 and V52, respectively.

A capacitor conductor pattern 60 is formed on the dielectric layer Lyr6. The capacitor conductor pattern 60 is connected to the capacitor conductor pattern 20 by the inductor via conductor pattern V60. The inductor via conductor pattern V60 functions as the inductor L1. Capacitor conductor pattern 60 and capacitor conductor patterns 51 and 52 form capacitors C3 and C4, respectively.

A ground conductor pattern 71 is formed on the dielectric layer Lyr7. The capacitor conductor pattern 60 and the ground conductor pattern 71 form a capacitor C1. Further, as already described, the ground conductor pattern 71 is connected to the ground conductor pattern 11 by each of a plurality of via conductor patterns (not shown).

As described above, the direction identification mark DM is formed on the upper surface UF of the dielectric layer Lyr8.

Referring to FIG. 1 again, at the resonance frequency fr1 of the LC resonator 10 defined by the following equation (1), the impedance of the LC resonator 10 becomes very large (approaching infinity). In the vicinity of the resonance frequency fr1, the signal from the input / output terminal P1 or P2 is difficult to pass through the LC resonator LC10, and the signal is easily transmitted from one input / output terminal to the other input / output terminal. In other words, the resonance frequency of the bandpass filter 1 at which the insertion loss is minimized is a frequency near the resonance frequency fr1 of the LC resonator 10. The resonance frequency of the bandpass filter 1 can be adjusted by adjusting the resonance frequency fr1.

Also, at the resonance frequency fr2 of the LC series resonator SLC defined by the following formula (2), the impedance of the LC series resonator SLC becomes very small (approaching 0). In the vicinity of the resonance frequency fr2, the signal from the input / output terminal P1 or P2 easily passes through the LC resonator LC10. As a result, of the signal from one input / output terminal, the proportion lost through the LC resonator LC10 increases. That is, an attenuation pole in which the insertion loss of the bandpass filter 1 is maximized occurs at a frequency near the resonance frequency fr2. By adjusting the resonance frequency fr2, the frequency of the attenuation pole of the bandpass filter 1 can be adjusted.

Hereinafter, how the characteristics of the band-pass filter 1 change when the resonance frequencies of the LC resonator 10 and the LC series resonator SLC are changed will be described with reference to FIGS.

FIG. 5 is a plan view of the bandpass filter 1 shown in FIG. 4 from the Y-axis direction. Referring to FIG. 5, when the length of inductor via conductor pattern V60 (inductor L1) (distance between capacitor conductor patterns 20 and 60) D1 is changed, the inductance of inductor L1 changes, and the resonance frequency of LC resonator 10 changes. The resonance frequency fr2 of fr1 and the LC series resonator SLC changes simultaneously. In this case, how the characteristics of the bandpass filter 1 change will be described with reference to FIG.

When the area of the capacitor conductor pattern 20 is changed, the capacitance of the capacitor C2 is changed, and the resonance frequency fr2 of the LC series resonator SLC is changed. How the characteristics of the bandpass filter 1 change in this case will be described with reference to FIG.

When the distance D2 between the capacitor conductor pattern 60 and the ground conductor pattern 71 or the area of the capacitor conductor pattern 60 is changed, the capacitance of the capacitor C1 changes, and the resonance frequency fr1 of the LC resonator 10 changes. How the characteristics of the bandpass filter 1 change in this case will be described with reference to FIGS.

FIG. 6 is a diagram showing the insertion losses IL101 to IL103 when the length of the inductor via conductor pattern V60 (inductance of the inductor L1) is changed in three stages. In FIG. 6, the amount of attenuation (dB) on the vertical axis is shown as a negative value. The larger the absolute value of attenuation, the greater the insertion loss. The same applies to FIGS. 7 to 9 and FIG. It means that the larger the insertion loss, the larger the proportion of the signal lost in the bandpass filter 1 in the signal input to the bandpass filter 1. Therefore, a smaller insertion loss is preferable.

In FIG. 6, the lengths of the inductor via conductor patterns V60 when the insertion loss is represented by IL101 to IL103 are distances D11 to D13 (D11> D12> D13), respectively. When the insertion loss is represented by IL101 to IL103, the resonance frequencies of the bandpass filter 1 are frequencies f1 to f3 (f1 <f2 <f3), respectively. When the insertion loss is represented by IL101 to IL103, the frequencies of the attenuation poles are frequencies f11 to f13 (f11 <f12 <f13), respectively.

As the length of the inductor via conductor pattern V60 decreases, the inductance of the inductor L1 decreases. As the inductance value decreases, the resonance frequency fr1 of the LC resonator 10 increases (see equation (1)), so that the resonance frequency of the bandpass filter 1 increases as shown in FIG. In the band pass filter 1, the resonance frequency of the band pass filter 1 can be adjusted by adjusting the length of the inductor via conductor pattern V60.

Also, the smaller the length of the inductor via conductor pattern V60 is, the higher the resonance frequency fr2 of the LC series resonator SLC is (see equation (2)), and thus the frequency of the attenuation pole of the bandpass filter 1 is also increased. In the band pass filter 1, the frequency of the attenuation pole of the band pass filter 1 can be adjusted together with the resonance frequency by adjusting the length of the inductor via conductor pattern V60.

FIG. 7 is a diagram showing the insertion losses IL111, IL101, and IL112 when the area of the capacitor conductor pattern 20 (capacitance of the capacitor C2) is changed in three stages. The insertion loss IL101 shown in FIG. 7 is the same as the insertion loss IL101 shown in FIG. When the insertion loss is expressed by IL111, IL101, and IL112, the area of the capacitor conductor pattern 20 is areas S21 to S23 (S21> S22> S23), respectively. The frequencies of the attenuation poles of the bandpass filter 1 when the insertion loss is represented by IL111 and IL112 are frequencies f14 and f15 (f14 <f11 <f15), respectively.

The smaller the area of the capacitor conductor pattern 20, the smaller the capacitance of the capacitor C2. When the capacitor capacitance is decreased, the resonance frequency fr2 of the LC series resonator SLC is increased (see the equation (2)), and therefore the frequency of the attenuation pole of the bandpass filter 1 is increased. In addition, the resonance frequency of the bandpass filter 1 when the insertion loss is expressed by IL111, IL101, and IL112 changes as the capacitance of the capacitor C2 changes (see Expression (1)). However, the change in insertion loss after the resonance frequency is almost the same when the insertion loss is expressed by IL111, IL101, and IL112. That is, the change in the area of the capacitor conductor pattern 20 hardly affects the pass characteristics of the bandpass filter 1. By adjusting the area of the capacitor conductor pattern 20, it is possible to adjust the frequency of the attenuation pole of the bandpass filter 1 with little influence on the pass characteristics of the bandpass filter 1.

FIG. 8 is a diagram showing the insertion losses IL101 and IL121 together when the distance between the capacitor conductor pattern 60 and the ground conductor pattern 71 (capacitance of the capacitor C1) is changed in two stages. The insertion loss IL101 shown in FIG. 8 is the same as the insertion loss IL101 shown in FIG. The distance between the capacitor conductor pattern 60 and the ground conductor pattern 71 when the insertion loss is represented by IL101 and IL121 is the distances D21 and D22 (D21> D22), respectively. The resonance frequency of the bandpass filter 1 when the insertion loss is expressed by IL121 is a frequency f4 (f4 <f1).

As the distance between the capacitor conductor pattern 60 and the ground conductor pattern 71 decreases, the capacitance of the capacitor C1 increases. As the capacitance of the capacitor increases, the resonance frequency fr1 of the LC parallel resonator PLC decreases (see equation (1)), and therefore the resonance frequency of the bandpass filter 1 decreases. On the other hand, when the insertion loss is represented by IL121 and IL101, the frequency of the attenuation pole is a frequency in the vicinity of the frequency f11 and hardly changes. By adjusting the distance between the capacitor conductor pattern 60 and the ground conductor pattern 71, the resonance frequency can be adjusted with almost no change in the frequency of the attenuation pole of the bandpass filter 1.

FIG. 9 is a diagram showing the insertion losses IL101 and IL122 when the area of the capacitor conductor pattern 60 (capacitance of the capacitor C1) is changed in two stages. The insertion loss IL101 shown in FIG. 9 is the same as the insertion loss IL101 shown in FIG. The areas of the capacitor conductor pattern 60 when the insertion loss is expressed by IL101 and IL122 are areas S11 and S12 (S11 <S12), respectively. When the insertion loss is expressed by IL122, the resonance frequency and the frequency of the attenuation pole are frequencies f5 (f5 <f1) and f16 (f16 <f11), respectively.

As the area of the capacitor conductor pattern 60 increases, the capacitance of the capacitor C1 increases. In this case, since the resonance frequency fr1 of the LC parallel resonator PLC becomes low (see Expression (1)), the resonance frequency of the bandpass filter 1 becomes low. This correspondence is the same as the correspondence shown in FIG. However, in FIG. 9, when the insertion loss is represented by IL101 and IL122, the frequency of the attenuation pole has a larger difference than that in FIG.

When the area of the capacitor conductor pattern 60 is changed, the electric field distribution in the capacitor C1 is changed, and the coupling state between the capacitors C1 and C2 can be changed not to be ignored. In that case, the change in the area of the capacitor conductor pattern 60 has a non-negligible effect not only on the resonance frequency of the LC resonator 10 but also on the resonance frequency of the LC series resonator SLC. As a result, the frequency of the attenuation pole of the bandpass filter 1 can also change to an extent that cannot be ignored.

On the other hand, when the distance between the capacitor conductor pattern 60 and the ground conductor pattern 71 is changed, the distribution of the electric field in the capacitor C1 hardly changes. Since the coupling state between the capacitors C1 and C2 hardly changes, even if the area of the capacitor conductor pattern 60 is changed, the frequency of the attenuation pole of the bandpass filter 1 hardly changes.

It is possible to adjust the resonance frequency of the bandpass filter 1 by adjusting either the distance between the capacitor conductor pattern 60 and the ground conductor pattern 71 or the area of the capacitor conductor pattern 60. However, when it is not desired to change the frequency of the attenuation pole of the bandpass filter 1, it is preferable to adjust the distance between the capacitor conductor pattern 60 and the ground conductor pattern 71.

Further, when the bandpass filter 1 is manufactured as a laminated body, in order to adjust the area of the capacitor conductor pattern 60, it is necessary to change the conductor pattern formed on the dielectric layer. On the other hand, adjustment of the distance between the capacitor conductor pattern 60 and the ground conductor pattern 71 can be realized by changing the thickness of the dielectric layer. Therefore, the adjustment of the distance between the capacitor conductor pattern 60 and the ground conductor pattern 71 is easier than the adjustment of the area of the capacitor conductor pattern 60. From the viewpoint of ease of adjustment, it is preferable to adjust the distance between the capacitor conductor pattern 60 and the ground conductor pattern 71.

As described above, in the LC filter according to Embodiment 1, one end of the inductor is galvanically isolated from the ground node by the first capacitor, and the other end of the inductor is galvanically isolated from the ground node by the second capacitor. Has been. Since the inductor is galvanically separated from the ground electrode connected to the ground node, the ground electrode and other conductors connected to the ground electrode are suppressed from functioning as an inductor. As a result, it is possible to suppress the LC filter characteristics from deviating from the desired characteristics.

In Embodiment 1, by adjusting the length of the inductor via conductor pattern, both the resonance frequency of the bandpass filter and the frequency of the attenuation pole can be adjusted. The resonance frequency of the bandpass filter can be adjusted by adjusting the distance between the conductor patterns constituting the first capacitor or the area of the conductor pattern. By adjusting the distance between the conductor patterns constituting the second capacitor, it is possible to adjust the frequency of the attenuation pole of the bandpass filter with little influence on the pass characteristic of the bandpass filter.

[Embodiment 2]
In the first embodiment, the case where the LC filter according to the present invention includes one LC resonator has been described. The LC filter according to the present invention can include a plurality of LC resonators. In the second embodiment, a case where the LC filter according to the present invention includes four LC resonators will be described.

FIG. 10 is an exploded perspective view showing an example of a laminated structure of the bandpass filter 2 according to the second embodiment. In FIG. 10, the dielectric layers Lyr2 and Lyr6 shown in FIG. 4 are replaced with Lyr2B and Lyr6B, respectively. Since the dielectric layers other than Lyr2B and Lyr6B are the same as those in FIG. 4, the description will not be repeated.

Capacitor conductor patterns 21 to 24 are formed on the dielectric layer Lyr2B. Capacitor conductor patterns 61 to 64 are formed on the dielectric layer Lyr6B. Capacitor conductor patterns 61-64 are connected to capacitor conductor patterns 21-24 by inductor via conductor patterns V61-V64, respectively.

FIG. 11 is a plan view of the dielectric layers Lyr6B to Lyr2B of the bandpass filter 2 shown in FIG. As shown in FIG. 11, the bandpass filter 2 includes LC resonators LC21 to LC24. The LC resonators LC21 to LC23 are adjacent to each other. The LC resonator LC24 is adjacent to the LC resonators LC22 and LC23.

The LC resonator LC21 includes capacitor conductor patterns 21 and 61 and an inductor via conductor pattern V61 connecting the capacitor conductor patterns 21 and 61. The capacitor conductor pattern 61 forms a capacitor C3 together with the capacitor conductor pattern 51, and insulates the inductor via conductor pattern V61 from the input / output terminal P1 in a DC manner.

The LC resonator LC22 includes capacitor conductor patterns 22 and 62 and an inductor via conductor pattern V62 connecting the capacitor conductor patterns 22 and 62. The LC resonator LC23 includes capacitor conductor patterns 23 and 63 and an inductor via conductor pattern V63 that connects the capacitor conductor patterns 23 and 63.

The LC resonator LC24 includes capacitor conductor patterns 24 and 64 and an inductor via conductor pattern V64 connecting the capacitor conductor patterns 24 and 64. The capacitor conductor pattern 64 forms a capacitor C4 together with the capacitor conductor pattern 52, and insulates the inductor via conductor pattern V64 from the input / output terminal P2.

Since the LC resonators LC21 to LC23 are adjacent to each other, magnetic coupling occurs between the inductor via conductor patterns of the LC resonators LC21 to LC23. That is, the magnetic coupling M12 is generated between the inductor via conductor patterns V61 and V62. A magnetic coupling M23 is generated between the inductor via conductor patterns V62 and V63. A magnetic coupling M13 occurs between the inductor via conductor patterns V61 and V63. The magnetic coupling is coupling via magnetic flux in which the magnetic flux between the inductors changes with a change in the current flowing through one inductor and an induced electromotive force is generated in the other inductor.

Since the LC resonator LC24 is adjacent to the LC resonators LC22 and LC23, magnetic coupling occurs between the LC resonators LC22 and LC24 and between the LC resonators LC23 and LC24. That is, the magnetic coupling M24 is generated between the inductor via conductor patterns V62 and V64. A magnetic coupling M34 is generated between the inductor via conductor patterns V63 and V64.

In the bandpass filter 2, the LC resonators LC21 to LC24 are not arranged linearly, but are arranged in a staggered manner so that each LC resonator is adjacent to at least the other two LC resonators. By arranging the LC resonators LC21 to LC24 in a staggered manner, the magnetic coupling between the LC resonators becomes stronger than the linear arrangement. As a result, signal transmission between the inductors is promoted, and the pass band of the bandpass filter 2 can be expanded.

In addition, by arranging the LC resonators LC21 to LC24 in a staggered manner, it is possible to effectively utilize the limited space inside the stacked body, compared to the case where they are arranged in a straight line. As a result, the dead space inside the laminate is reduced, and the bandpass filter 2 can be downsized.

FIG. 12 is a diagram showing both the insertion loss IL20 and the reflection loss RL20 of the bandpass filter 2 shown in FIG. The larger the absolute value of attenuation, the greater the reflection loss. It means that the larger the reflection loss, the larger the proportion of the signal input to the bandpass filter 2 that is not reflected inside the bandpass filter 2 and does not return. Therefore, it is preferable that the reflection loss is large.

As shown in FIG. 12, the insertion loss IL20 becomes almost flat as the attenuation approaches 0 in the frequency band of frequencies f21 to f22. The reflection loss RL20 has a maximum in the frequency band of frequencies f21 to f22. In the bandpass filter 2, the reflection loss is maximized in the frequency band of frequencies f21 to f22 where the insertion loss IL20 is flattened and minimized, and typical characteristics of a practical bandpass filter are realized. Has been.

In the frequency band of frequencies f21 to f22, the maximum value and the minimum value appear alternately in the reflection loss RL20. Such a change in the reflection loss RL20 is a typical change that occurs when a plurality of LC resonators are magnetically coupled. A wide band of the pass band of the bandpass filter 2 is realized by magnetically coupling the plurality of LC resonators.

As described above, according to the LC filter according to the second embodiment, one end of each inductor of the first to fourth LC resonators is galvanically isolated from the ground node by the first capacitor, and the other end of each inductor is The second capacitor is galvanically isolated from the ground node. Since each inductor of the first to fourth LC resonators is galvanically isolated from the ground electrode connected to the ground node, the ground electrode and other conductors connected to the ground electrode are suppressed from functioning as inductors. The As a result, it is possible to suppress the LC filter characteristics from deviating from the desired characteristics.

In Embodiment 2, the first to third LC resonators are adjacent to each other. A fourth LC resonator is adjacent to the second and third LC resonators. Therefore, magnetic coupling occurs between the resonators. As a result, the performance of the LC filter can be improved. In addition, since the first to fourth LC resonators are arranged in a staggered manner, the LC filter can be reduced in size.

The embodiments disclosed this time are also scheduled to be implemented in appropriate combinations within a consistent range. The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

1, 2, band pass filter, 11, 71 ground conductor pattern, 20-24, 51, 52, 60-64 capacitor conductor pattern, C1-C4 capacitor, DM direction identification mark, GN ground node, GND ground electrode, L1 inductor, LC10, LC21 to LC24, LC resonator, Lyr1 to Lyr8, Lyr2B, Lyr6B dielectric layer, P1, P2 input / output terminals, SLC LC series resonator, V51, V52 via conductor pattern, V60 to V64 inductor via conductor pattern.

Claims (8)

An LC resonator in which a plurality of dielectric layers are stacked in the stacking direction,
First and second capacitors;
An inductor connected between the first capacitor and the second capacitor;
One end of the inductor is galvanically isolated from a ground node by the first capacitor;
The LC resonator, wherein the other end of the inductor is galvanically isolated from the ground node by the second capacitor. First and second ground conductor patterns respectively formed on the first and second dielectric layers included in the plurality of dielectric layers;
A first capacitor conductor pattern formed in a third dielectric layer between the first and second dielectric layers included in the plurality of dielectric layers and forming the first capacitor together with the first ground conductor pattern When,
A second capacitor conductor pattern formed in a fourth dielectric layer between the second and third dielectric layers included in the plurality of dielectric layers and forming the second capacitor together with the second ground conductor pattern; When,
The LC resonator according to claim 1, further comprising an inductor via conductor pattern that connects the first capacitor conductor pattern and the second capacitor conductor pattern and functions as the inductor. The LC resonator according to claim 2, wherein the first ground conductor pattern is connected to the second ground conductor pattern by a plurality of via conductor patterns. 4. The LC resonator according to claim 2, wherein an area of the first capacitor conductor pattern is different from an area of the second capacitor conductor pattern. The distance between the first capacitor conductor pattern and the first ground conductor pattern is different from the distance between the second capacitor conductor pattern and the second ground conductor pattern. LC resonator. LC resonator according to any one of claims 1 to 5,
First and second terminals;
A third and a fourth capacitor;
One end of the inductor is galvanically insulated from the first terminal by the third capacitor,
The LC filter, wherein one end of the inductor is galvanically insulated from the second terminal by the fourth capacitor. A first to third LC resonator according to any one of claims 1 to 5,
The first to third LC resonators are LC filters adjacent to each other. The fourth LC resonator according to any one of claims 1 to 5;
First and second terminals;
A third capacitor and a fourth capacitor;
One end of the inductor of the first LC resonator is galvanically insulated from the first terminal by the third capacitor,
One end of the inductor of the fourth LC resonator is galvanically insulated from the second terminal by the fourth capacitor,
The LC filter according to claim 7, wherein the fourth LC resonator is adjacent to the second and third LC resonators.

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